1. Field of the Invention
The invention relates to an active-matrix display device, which is particularly suitable for a display device capable of high-aperture and small-sized pixel memory-based display operations.
2. Description of the Related Art
A TFT (Thin Film Transistor) liquid crystal display device with a switching element in each pixel is widely used as the display device of a personal computer and the like. Such a TFT display device is also used as the display device of a mobile terminal, such as a mobile phone. The display device used in a mobile terminal needs to be more compact and consume less power than conventional liquid crystal display devices.
Particularly, when the power supply of a mobile terminal is a battery or the like, the display device, like other components, needs to reduce power consumption. To this end, it has been proposed to impart a memory capability to each pixel of the liquid crystal display device.
U.S. Pat. No. 7,057,596 describes a capacitor connected not only to two pairs of transistors that holds an image signal but also to a pixel electrode. In this document, the charge accumulated in the capacitor is used to control the data write state. However, in U.S. Pat. No. 7,057,596, a static RAM is used to hold data, and no consideration is given to the increased area occupied by a circuit using an inverter circuit formed of a pair of transistors.